Disconnector



6, 1963 w. F. RILEY 3,100,246

DISCONNECTOR Filed Feb. 20, 1961 ll HHHH .4 Q FIGI INVHVTOR. WILLIAM ERILEY BY W ?ZM 4%.

ATTORNEYS United grates Patent 3,100,246 DISCONNECTOR William F. Riley,Ber-Wyn, 111., assignor to Joslyn Mfg. and Supply Co., Chicago, 111., acorporation of Illinois Filed Feb. 20, 1961, Ser. No. 90,325 7 Claims.(Cl. 200-115) This invention relates to disconnectors adapted for use inconjunction with lighting arresters for the protection of electrictransmission lines.

It has been the practice to provide a disconnector for use inconjunction with a lightning arrester for the purpose of permanentlyopening the circuit between the arrester and ground when the arresterhas failed or is malfunctioning. It is desirable to disconnect thearrester from the circuit after such failure or malfunctioning in orderto prevent an abnormal flow of current through the failed arrester toground, which current, unless interrupted, results in the opening offuses or circuit breakers and, hence, causes outage of the circuit untilthe faulty arrester can be located and replaced. In order to facilitatethe finding and replacement of the faulty arrester, it is desirable toprovide a disconnector which will visually indicate, upon casualinspection, that the arrester is faulty.

A common type of disconnector in present use is one which employs anexplosive charge to break a thin section of its housing thusdisconnecting the circuit and giving a visual indication of arresterfailure. These disconnectors employ a spark gap in which the heatgenerated by the arc across the gap ignites the explosive charge tosever the thin section of the housing and, hence, disconnects thearrester from the circuit. During a sudden surge of voltage across thegap for a short duration of time as might be caused by lightning orother disturbance on the line, the heat generated by the arc is notsufficient to ignite the explosive. However, if, after the surge hasPassed, an abnormally high current is present because of the failure ofthe arrester, the heating caused by the prolonged duration of the arcwill ignite the explosive charge, thus disconnecting the arrester beforefuses or circuit breakers are opened on the line. In order to preventthe buildup of a potential difference across the spark gap, whichbuildup causes radio interference because of the sparkover or coronaeffect resulting therefrom, the electrodes of the gap are shunted by aresistor or other impedance thereby discharging any charge accumulatingon the electrodes. A common difliculty in these present disconnectors isthat many times during their installation the thin section of theirhousing is ruptured by the lineman applying too much torque whenattaching the ground lead and, in view of this problem, somemanufacturers recommend the use of torque-wrenches to reduce breakageduring installation.

Therefore, it is an important object :of the present invention toprovide a new and improved disconnector of the general characterdescribed above but so constructed and arranged that the thin section ofthe housing is not easily ruptured during installation. I

A further object of the invention is to provide a disconnector of thecharacter indicated which is simple in construction, easy to manufactureand relatively low in cost.

Another important object of the present invention is to provide a newand improved disconnector of simple, compact construction for use inconjunction with a lightning arrester for the purpose of disconnectingthe arrester from the circuit when an abnormally high follow current ispresent due to arrester failure and, at the same time, for minimizingsparkover effect across the arc gap of the disconnector, thuseliminating radio interference.

According to the present invention, the foregoing and other objects arerealized by providing a disconnector comprising an insulating housing orshell having a thin section at one end thereof and containing a firstterminal adapted to be connected to a lightning arrester and a secondterminal extending through the thin section of the housing forconnection to a ground lead. The terminals are positioned in spacedrelation to define a spark gap and an insulating spacer is disposedbetween the terminals and around the gap. An impedance carried by thespacer is electrically connected between the two terminals to shunt thespark gap, and explosive means are contained within one [of theterminals for rupturing the thin section of the housing in order toexpel the second terminal from the housing. Any torque applied to thesecond terminal during assembly of the ground.

FIG. 2 is an exploded, perspective view of the dis-.

connector shown in FIG. 1 and illustrates the various parts making upthe disconnector.

Referring now to FIGS. 1 and 2, a disconnector characterized by thefeatures of the present invention is there indicated generally by thereference numeral 10 and comprises a generally bell-shaped insulatinghousing or shell 12 having at the smaller end a thin, fracturablesection 14 provided with a central aperture 15. As will be evident fromFIG. 1, the section 14 is substantially thinner than the remainingportions of the housing 12 so that it will rupture along the regionindicated at X when subjected to a downward force as described morefully hereinafter.

As was indicated previously, the disconnector 10 includes a firstterminal means 18 located adjacent the open or large end of the housing12 and a second terminal means 20 adjacent the smaller end. The firstterminal means includes an externally threaded, electrically conducting,cylinder 19 inserted into an internally threaded portion 12a of thehousing 12. In order to secure the disconnector to the bot-tom of alightning arrester 16, both mechanically and electrically, the cylinder19 is provided with an axial threaded bore 19a for receiving a terminalbolt 22 of the lightning arrester 16. The external threads of thecylinder 19 are provided with a suitable thread sealant in order toprevent disengagement of the cylinder 19 from the housing 12 and toeffect a weather-tight seal therebetween. Means, such as a set ofrecesses 24, are provided in the outer face of the cylinder forengagement by a wrench or tool to permit the cylinder 19 to be threadedinto the housing 12. A gasket 26 is seated within an annular recess 12bin the upper rim of the housing and engages the lower end of thearrester 16 to effect a moisture-tight seal.

The lower surface of the cylinder 19 is provided with a plurality ofdepending radially spaced lugs 28 which are seated within spacedrecesses 30 in a cylindrically shaped, insulating spacer 32 disposedtherebelow in order to interlock these two members to prevent relativerotaa rounded head 36 of a hollow stemmed terminal cap 38 forming part'of the first terminal'means 18. The head 36 is firmly seated within therecess 34 by the spacer 32, thus forming a good electrical connectionbetween the two members making up the first terminal means. The hollowstem 40 of the terminal cap 38'extends through a central bore 44 in thespacer 32 and is at least partially filled with anexplosive material 42.The extreme, lower end of the stem 40 protrudes into an axiallydisposed, square, shaped spark gap containing recess 46 formed in thelower end of the spacer 32. The recess 46 also receives a portion of thesecond terminalmeans 2.0 which cooperates with the first terminal means18' to define a spark gap 54. More specifically, the second terminalmeans 20 includes an upper, square head 48 extending into the recess 46to form an interlock for preventing relative rotative movement'betweenthe spacer 32 and the terminal means 20 and for transmitting betweenthese two members torsion forces applied to the second terminal means asdescribed below. The square head 48 is provided'with an axial recess 52somewhat larger in diameter than the outside diameter of the hollow stem40013 the terminal cap 38, thus forming an air space defining the sparkgap 54.

The second terminal means 20 is provided with an enlarged washer-likeportion 56 formed integrally with and disposed directly below the squarehead 48. This washer-like portion 56 engages the lower face of theinsulating spacer 32 and thus serves to limit the depth of insertion ofthe head 43 into the recess 46, thereby retaining the lower terminalmeans 20 in fixed spaced relationship with the terminal cap 38 andmaintaining a spark gap of predetermined size. An impedance 58, such asa resistor or a coil, is disposedwithin a through passage 60 defined inthe insulating spacer 32.. The passage 60 is spaced from and extendsparallel tothe axial bore 44; The upper end of the impedance 58 iselectrically connected to the lower face of the cylinder 19'by means ofan electrically conducting, compression spring 62, while the lower endofthe impedance 58 is electrically connected to the upper face of the.washerlike portion 56 by means of a similar spring64. Thus,,,

it will be apparent that the spark gap 54 is electrically shunted by theimpedance 58. A gasket 66is interposed between the lower surface, ofvthe.washer-like portion 56 and the thin fracturable section 14 of the.housing 12 to. efiect a seal therebetween.

The terminal means 20 alsorincludes athreaded shank 68 formed integrallywith the head 48 andthe washerlike portion 56. A collar 70 is drivefitted onto the shank 68 and, seated tightly againstthewasher-likeportion 56. The collar 70 extends through the aperture 15and, since it is slightly thicker than the section 14, it extendsslightly beyond the plane of the lower face of the latter section. Theshank 68 extends well below the collar 70 and receives a lug nut 74which, when tightened, seats against the collar and, hence, does notexert pressure onthe. thin, fracturable section 14.

A clamping member 76 is slipped onto the shank 68 and a lock nut 78 isalso threaded onto the shank. 68 forv thepurpose of rigidly securing aground lead 80to the second terminal means 20. When the lug nut 74 andthe lock nut76 aretightened, for example, by use of a wrench, the torqueapplied thereto is transmitted through the terminal means 20,-throughthe. insulating spacer 32, through the first terminal means 18 and tothe bolt 22 depending from the arrester 16 and, as a result, the thinfracturable section 14 is not subject to rupture due to excesstightening torque.

During the normal operation of the arrester 16, the

disconnector operates as a spark gap in a manner well known in the art.Thus, when short duration surges caused by lightning or other linedisturbances are present, current from the arrester 16 passes throughthe cylinder 19 to therterminal. cap 38, jumps the spark gap 54- to thesecond terminal means 20 and is dissipated through the ground lead 86 toground. The heat caused by arcing across the spark gap 54 during such ashort duration surge is not sufiicient to ignite the charge 42. However,if for any reason the arrester 1'6 fails to interrupt the current flowafter the surge has passed so that an abnormal current continues to fiowthrough the arrester 16, the heat generated by the arc across the sparkgap 54 becomes suflicient to ignite the explosive material 42 thuscreating an explosive force acting against the head 48 of the terminalmeans 20. The washer-likev portion 56 is thus urged downwardly torupture'the thin, fracturable: section 14' along the region indicated atX in FIG. 1.

and the entire terminal means 20 falls away from the assembly to breakthe circuit between the arrester 16- and ground. .Since the terminalmeans 20 is securely attached to the ground lead 80, it is freelysuspended and, hence, can be seen upon casual inspection by a groundobserver to indicate that the arrester 16 has failed and must bereplaced. The shunting impedance 58 serves to dissipate to ground anycharge accumulating on the first terminal means 18 thus preventing theformation of corona or sparking which might cause interference to radiosor the like.

While a particular embodiment of the invention has been shown, it willbe understood, of course, that the invention is not limited theretosince many modifications will readily occur to those skilled in this artand it is therefore contemplated by the appended claims to cover anysuch modifications as fall within the true spirit and scope of theinvention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is I. In a disconnector adapted for use with'alightning arrester, an insulating shell having a portion with arelatively thin: wall section, first terminal means Within said shelladapted to be connected to said arrester, second terminal meansextending into said shell and adaptedto be connected to a ground lead,an insulating spacer within said shell and disposed between said firstand second terminal means, said first terminal means including a portionextending through said spacer and separated from said second terminalmeans to form a spark gap, explosive means contained in one of saidterminal means for rupturing said shell along said thin wall section andfor thus expelling said second terminal means upon an abnormal flow ofcurrent across said spark gap for a predetermined time, and said firstand second terminal meansincluding members interlocked with said spacerto join said spacer and both terminal members to form a unitary torquetransmitting assembly for transmitting torque between the two terminalmembers independently of the. thin wall section of the shell.

2. In a d-isconnector, the combination as set forth inclaim 1, andadditionally including impedance means second terminal means.

3. The combination defined in claim 2 wherein said" spacer is providedwith a passage therethrough and wherein said impedance means is disposedwithin said passage:

and is electrically connected at its opposed ends to said first andsecond terminal means respectively.

4. In a disconnector adapted for use with a lightning arrester, aninsulating housing having a portion with a relatively thin wall section,first terminal means thread-- ably engaged within said housing andadapted to be connected'to said arrester, second terminal meansextending through an aperture defined in said thin wall section andadapted to be connected to a ground lead, an insulating spacer withinsaid housing disposed between'said first and second terminal means, saidfirst terminal means including a portion extending through said spacerand separated from said second terminal means to form a spark gap,explosive means contained in one ofxsaidterminal means for rupturingsaid shell along said thin Wall section and for thus expelling saidsecond terminal means upon an abnormal liow of current across said sparkgap for a predetermined time, and said first and second terminal meansincluding members interlocked with said spacer to join said spacer andboth terminal members to form a unitary torque transmitting assembly fortransmitting torque between the two terminal members independently ofthe thin wall section of the shell.

5. In a disconnector adapted for use with a lightning arrester, aninsulating shell having a portion with a relatively thin wall section,first terminal means adapted to be connected to said arrest-er, secondterminal means adapted to be connected to a ground lead, an insulatingspacer within said shell disposed between said first and second terminalmeans, said first terminal means including a cylindrical memberthreadably engaged within said shell and a second member extendingthrough said spacer and containing explosive means, said second terminalmeans extending into and interlocking with said spacer and spaced fromsaid explosive material containing memher to form a spark gap, saidexplosive means being adapted to rupture said thin wall section and forthus expelling said second terminal means from said housing upon anabnormal flow of current across said spark gap for a predetermined time,and said first and second terminal means including members interlockedwith said spacer to join said spacer and both terminal members to form aunitary torque transmitting assembly for transmitting torque between thetwo terminal members independently of the thin wall section of theshell.

*6. The combination defined in claim 5 wherein said second terminalmeans includes a radially extending stop engaging said spacer andlimiting the extension of said second terminal means into said spacer.

7. In a disconnector adapted for use with a lightning arrester, aninsulating shell having an inturned end flange of relatively thin wallsection and defining a central aperture, first terminal means adapted tobe connected to said 4 arrester within said shell, second terminal meansadapted to be connected to a ground lead, a generally cylindricalinsulating spacer Within said shell disposed between said first andsecond terminal means and having a central axial bore therethrough, arecess at one end of said spacer in communication with said bore, saidfirst terminal means including a generally cylindrical first memberhaving external threads threadedly engaged with said shell and a secondmember extending into said bore in said spacer and containing explosivemeans, said second terminal means extending into said recess andinterlocking with said spacer and spaced from said second member to forma spark gap, said explosive means being adapted to r-upture said thinwalled end flange and to expell said second terminal means from saidshell upon an abnormal flow of current across said spark gap, for apredetermined time, a collar on said second terminal means seatedagainst said one end of said spacer and having a diameter greater thanthe diameter of said aperture defined by said thin walled end fiange ofsaid shell, said second terminal means having a shank portion extendingthrough said aperture and a nut threaded onto said shank portion forattaching said ground lead to said second terminal means, spacing meansdefined on said shank portion extending slightly outward of said shellfor preventing said nut from touching said shell when tightened on saidshank portion, and said first and secend terminal means and said spacerincluding elements interlocked with one another to join said spacer andsaid first and second terminal means to form a unitary torquetransmitting assembly for transmitting torque between the two terminalmeans independently of said thin walled end flange of the shell.

References Cited in the file of this patent UNITED STATES PATENTS2,551,858 Stoelting May 8, 1951 2,989,608 Hicks June 20, 1961 FOREIGNPATENTS 555,349 Great Britain Aug. 18, 1943 826,262 France Mar. 28, 1938

1. IN A DISCONNECTOR ADAPTED FOR USE WITH A LIGHTING ARRESTER, ANINSULATING SHELL HAVING A PORTION WITH A RELATIVELY THIN WALL SECTION,FIRST TERMINAL MEANS WITHIN SAID SHELL ADAPTED TO BE CONNECTED TO SAIDARRESTER, SECOND TERMINAL MEANS EXTENDING INTO SAID SHELL AND ADAPTED TOBE CONNECTED TO A GROUND LEAD, AN INSULTING SPACER WITHIN SAID SHELL ANDDISPOSED BETWEEN SAID FIRST AND SECOND TERMINAL MEANS, SAID FIRSTTERMINAL MEANS INCLUDING A PORTION EXTENDING THROUGH SAID SPACER ANDSEPARATED FROM SAID SECOND TERMINAL MEANS TO FORM A SPARK GAP, EXPLOSIVEMEANS CONTAINED IN ONE OF SAID TERMINAL MEANS